Research On The Relationship Of Soil Nitrogen Transofrmation And Utilization Of Wheat Varities In Different Nitrogen Efficiency

The experiment was carried out at Henan Agricultural UniversityScience Park in2011-2013, we investigated nitrogen accumulation and nitrogenabsorption efficiency of4wheat varieties, under the condition of field, and thenstudied mechanism and machine utilization efficiency of nitrogen from the soilnitrogen transformation of wheat root activity, microbial biomass and activity of soilurease and protease activity. The results show that:Different wheat varieties with the same nitrogen level showed different nitrogenaccumulation and uptake efficiency of nitrogen. With the increasing of nitrogen, thewheat nitrogen accumulation increased. The difference between the wheat varietiesunder the condition of low nitrogen level is not obvious, increment of nitrogenapplication amount increased differences in the nitrogen uptake efficiency amongvarieties. Throughout the study period, the nitrogen accumulation of the two wheatvarieties Yanzhan4110and Hengguan35were less than that of Yumai49-198andAizao8. Based on the calculation of nitrogen absorption efficiency, the four varietieswere classified into two categories: high nitrogen absorption efficiency variety，including Yumai49-198and Aizao8, and low nitrogen absorption efficiency varietywith Yanzhan4110and Hengguan35.Wheat varieties with different nitrogen uptake expressed different root vigorefficiency, which mainly manifested in the jointing stage to blossom period, lownitrogen absorption efficiency variety Yanzhan4110and Hengguan35root activitywas significantly higher than the high absorption efficiency cultivar Yumai49-198and Aizao8. The difference between different varieties at late growth stage of rootactivity is not obvious.Nitrifying bacteria and denitrifying bacteria are also affected by the differentvarieties, the amount of nitrifying bacteria showed a down-up-down trend, and theammonifying bacteria kept more stable initially then increases rapidly during themature period, while the number of denitrifying bacteria also showed decreased firstlyand then increased, and the high nitrogen uptake efficiency variety have lower numberof root amid nitrifying bacteria and denitrifying bacteria, but ammonifiers amount donot have clear relationship with varieties, the amount of three types of bacteria in different varieties at latter growth stage was not significantly different.The number of nitrifying bacteria, denitrifying bacteria, ammonifying bacteriawas positively correlated with their activity, whose activity changing trend wereconsistent. Studies show that rhizosphere nitrification and denitrification activity ofYanzhan4110and Hengguan35was higher than that of Yumai49-198and Aizao8,and ammonifying bacteria activity between four varieties show no difference.Soil urease activity has been in a whole state of decline. Protease activity reachedthe maximum value after anthesis in15days, and the wheat varieties with highnitrogen uptake efficiency have higher soil urease and protease activity nitrogenapplication can improve the ammonification, nitrification and denitrification bacteriaactivity, which showed that of the four varieties in the research, rhizosphere microbialactivity of nitrogen transformation of the Yanzhan4110and Hengguan35is moreobviously affected by nitrogen application Nitrogen fertilizer also have biggerpromotion on soil urease and protease activities.With the increment of nitrogen application amount, soil moisture content, atjointing stage and blossom stage, decreased, and as for Yanzhan4110and Yumai49-198, their root activity of large variety of soil moisture content is significantlylower than that of Hengguan35and Aizao8.Nitrogen also promoted the dry matter accumulation of wheat, with the amountof nitrogen increasing, whole plant dry matter accumulation of wheat was also beenimproved, nitrogen application promoted the absorption and transformation ofnutrients in wheat.Changes of soil total nitrogen under different fertilization, is not entirelyconsistent, for N0and N8treatment in the study, rhizosphere soil total nitrogen in thegrowth period, expressed the up down “V-shape”, different wheat showed firstincreased and then decreased, reaches the maximum value during the blossom period,while in terms of N15treatment, its soil total nitrogen showed a N-like changingtrend, no obvious difference in soil total nitrogen content was observed amongdifferent varieties.Nitrogen use efficiency in wheat showed negative correlation with soil microbialactivity, was negatively correlated with nitrification activity at jointing stage, andsignificant negative correlation with denitrification activity in mature period. There isa positive correlation between soil urease and protease activity and nitrogen useefficiency in wheat, respectively in15days after flowering period, showed significant positive correlation and mature period.The yield of wheat was positively correlated with microorganism activitytransforming soil nitrogen, and negatively correlated with soil protease activity.Nitrification and denitrification activity significantly15days after flowering,significantly yield nitrification and urease activity and the mature period of wheat.